Electric clamp



(No Model.)

B. RASMUSSEN.

' ELECTRIC CLAMP. No. 458,188. Patented Aug. 25, 1891.

Full.

. 46 1 Jim/x UNITED STATES PATENT OFFICE.

EINAR RASMUSSEN, OF LYNN, MASSACHUSETTS, ASSIGNOR TO THE THOMSONELECTRIC IVELDING COMPANY, OF MAINE.

ELECTRIC CLAMP.

SPECIFICATION forming part of Letters Patent No. 458,188, dated August25, 1891.

Application filed December 19, 1890. Serial No. 375,202. (No model.)

To all whom it may concern.- ing and will allow any roughness or slightBe it known that I, EINAR RAsMUssEN, a irregularities in the work-piecesto be pressed 50 subject of the King of Norway and Sweden, into it,thereby making good contact over a and residing in Lynn, in the countyof Essex maximum amount of surface.

and State of Massachusetts, have invented a Illustrations of the mannerof applying my new and useful Improvement in Electric invention to metal-working apparatus are Clamps, of which the following, taken in conshownin the accompanying sheet of drawings. 5g nection with the accompanyingdrawings, is Figure 1 is a plan view of electric metala specification.working clamp showing the application of my My invention relates to animprovement in invention. Figs. 2 and 3 show my invention apparatus forelectric metal-working, and applied to other forms of electric clampinghas reference to the devices which make 0011- devices. tact with anddeliver current to the pieces to In Fig. 1 the part E is one terminal ofa be operated upon. source of current. Attached to this and in 15 In theart of electric welding and metalgood electrical connection therewith isthe working the current used is of very large volcontact-block A, whichis made of hard copnine and low intensity, and unless good elecper or agood conducting alloy. trical connection is provided between the sev- Cis the work-piece held in contact with the eral conducting parts heat isgenerated at the conducting-block by the jaw D.

- 20 points of contact, thus materially increasing At B is representedthe thin piece of soft the resistance and causing a considerableconducting materialsuch as copper ribbon I waste of power. or thelikewhich is especially referred to in In the commercial operation ofelectric this specification. metal-working apparatus it is found thatthe Fig. 2 illustrates the application of my in- 2 5 metals worked areoften rough and dirty on vention to the ordinary form of V-shaped theirsurfaces and must be used in this conclamps, and Fig. 3 shows the sameapplied to dition, in order not to increase the cost by exa special formof clamping device. pensive methods of preparation previous to Havingthus described my invention, what the welding or other operation. Thecon- I claim is 30 tinual abrasive action of these rough surfaces 1. Inelectric metal working apparatus, upon the conductorterminals orcontactthe combination, with conducting blocks or blocks causes a rapidand unequal wearing clamps, of a yielding material of good conaway ofthe contact-pieces, thus lessening ductivity in contact therewith,substantially their conducting-surface and greatly increasas and for thepurpose described.

3 5 ing the power required. 2. Electric clamps of Welding or metal-work-The object of my invention is to provide ing apparatus having the wholeor a portion means whereby the surfaces of the clamps of theircontact-surfaces covered by a yieldare protected from the abrasiveaction of the ing conducting material, substantially as dework-piecesand the best of electrical connecscribed.

40 tion obtained between said clamps and work- In testimony whereof Ihave signed my pieces. name to this specification, in the presence of Myinvention consists of the combination two subscribing witnesses, on this16th day of of ayielding piece of good conducting mate- December, A. D.1890. rial with the conducting devices of electric 45 welding andmetal-working apparatus. EINAR RASMUSSEN I prefer for the purposes of myinvention lVitnesses:

a thin piece of soft copper, owing to its excel- JOHN GIBBONEY, lentconductivity and also because it is yield- IVARREN B. LEWIS.

